266 MAMMALIAN ANATOMY 



oblique boundary is the outer boundary of the external pterygoid fossa, 

 and its continuation behind the foramen ovale. In its anterior internal 

 angle is the lower opening of the foramen rotundum, piercing the bone 

 obliquely outward, forward, and downward, so that when viewed from 

 below the inner or upper opening is not visible. Separated from this 

 opening by a flattened partition is the lower opening of the foramen 

 ovale, which also runs obliquely through the bone. A little behind 

 and lateral to the oval foramen is the posterior angle of this region, 

 which is prominent and marks the anterior termination of a roughened 

 articular area for the ectotympanic. It may be called the angular 

 spine. The zygomatic region slopes away from the foramen out- 

 ward and upward, and from behind forward and slightly upward, but 

 faces mainly downward, and lies in the same plane as the gleuoid 

 cavity. 



The scaphoid region (Fig. 190) is what remains of the lower 

 surface of the alisphenoid. Its boundaries are: in front, the inner 

 boundary of the zygomatic region ; within, the oblique groove for the 

 Vidian nerve; without, the outer, jagged, nearly straight, posterior part 

 of the general external border, joining the squamous of the temporal 

 bone ; and behind, a sharp, transverse, irregularly serrated border 

 which abuts against the petrous of the temporal bone. The inner 

 part of the surface is a shallow groove running obliquely backward 

 and outward. The inner front part is known as the scaphoid fossa, 

 and gives origin to the tensor palati muscle. The posterior part runs 

 slightly upward under the overhanging front of the auditory bulla, 

 forming; the roof of the long canal for the Eustachian tube and a 



C 1 o 



small anterior part of the roof of the tympanum. The outer part of 

 the surface, principally occupied by a narrow, oblique, and roughened 

 area, for articulation with the entotympanic portion of the bulla, is 

 marked by longitudinal grooves, producing between the surface and 

 the bulla the Glaserian fissure and the canal of Huguier. 



Nomenclature. Sphenoid is from two Greek words, sphen, a 

 wedge, and eides, like. It was introduced by Galen, and refers not 

 so much to its shape as to its wedge-like function in the base of the 

 human skull. The Latin names os sphenoidale, os sphenoideum, and 

 os sphenoides, the French le sphenoide, and the German das Keilbein, 

 all have the same signification. Another group of names is based on 

 the likeness of the bone to a flying insect : namely, os sphecoideum, 



